Oh so that's what "wedi" means.
The basic meaning of 'wedi' is 'after', this can be translated into english into other ways eg. Dw i wedi ymolchi - lit= 'I am after washing' which becomes 'I have washed'.
Wedi means lots of things, not just past.
So Time Is A Woman?
Like many languages Cymraeg gives nouns a gender. Just because the gender is feminine it doesn't automatically follow that the item itself is female.
Worth noting that the noun 'Amser' (Time) is actually masculine in Welsh. The pronoun 'Hi' is used here as a vague/non-specific 'It'.
It is also common to say in America: It is a half past seven.